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Comment on ”Stochastic considerations in optimal design of a microcatchment layout of runoff water harvesting“ by Gideon Oron and Gerda Enthoven
Author(s) -
Frasier Gary W.
Publication year - 1989
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr025i002p00333
Subject(s) - surface runoff , computer science , citation , operations research , library science , environmental science , hydrology (agriculture) , mathematics , engineering , geotechnical engineering , ecology , biology
In the introductory section it is stated, "It is commonly accepted that runoff efficiency, which is defined as the percent age of rainfall converted into runoff, is a decreasing function of the size of CA (catchment area) [Oron and Enthoven, 1987]." Later the authors note that "... the runoff efficiency is a decreasing function or the area size of the MC (micro catch ment) . . ." and indicate that the greater the overland flow distance, the less quantity of water that reaches the infiltrating area. This is illustrated by the authors' Figure 4. There is an unstated assumption in this approach. The runoff model pre sented is based upon the work of Diskin [1970], which as sumes a linear relationship between annual rainfall and runoff. Therefore there is no change in precipitation quantities (cither increase or decrease) with increasing catchment size; thus any change in runoff efficiency must be attributed to a change in water infiltration as the catchment area changes. As long as infiltration occurs, there will be an increased quantity of water losi from runoff due to the longer time the water is on the catchment surface. The longer the overland flow distance, the longer the time the water is subjected to potential loss to infiltration with a corresponding reduction in runoff quantity. Also, the rougher the catchment surface, the longer this water retention time.